Abstract: Apparatus for detecting the direction of motion from a reference signal, R, and a quadrature signal, Q, derived from the output signals X+0 and X+90 of a position transducer, wherein the polarity of the reference signal alternates with every fixed increment of motion of a transducer and the quadrature signal which maintains phase difference of +90.degree. or -90.degree. with respect to the reference signal depending on the direction of motion, is comprised of: digital means for producing a narrow pulse, P, at each low-to-high transition of the quadrature signal and a narrow pulse, N, at each high-to-low transition of the quadrature signal; means for determining the direction of motion from these narrow pulses and the reference signal once during each half cycle of the reference signal, and means for storing this direction information until a subsequent determination is made in order to provide a continuous signal indicating the direction of motion.
June 5, 1978
Date of Patent:
June 5, 1979
Ashok K. Desai, Bipinchandra V. Gami, Eric M. Dunstan
Abstract: A medium capacity peripheral processing system provides sophisticated interactive human communication without the extremely large, expensive memory systems that are normally associated with a main frame computer. The system includes a data bus interconnecting a 16 bit parallel processor, a random access memory having up to 64K words of memory storage, up to eight magnetic tape files, up to eight magnetic disk files, a key station multiplexer, and selector channels providing additional communication capabilities. The selector channels permit optional communication with a main frame computer system, a remote data entry system which may be a simple CRT key station or another peripheral processing system, a high speed optical character reader (OCR), a line printer, a computer output microfilm (COM) unit, or other data processing systems or subsystems. The key station multiplexer provides communication of serial address, data and control signals for up to 64 addressable, CRT key station terminals.
Abstract: Hardware duplication at each of a plurality of CRT key stations is minimized and centralized control is maintained by performing many traditional CRT key station operations under software control by a central processing unit. Simplified CRT key stations include circuitry providing automatic key stroke repeat for continuously actuated keys only after receipt of a repeat enable signal from the central processing unit for each separate repeat and a tone generator responsive to commands from the central processing unit. The tone generator includes a key click circuit to audibly indicate each completion of key activation. CRT key station circuitry inserts a configuration code with each key stroke data word which indicates one of a plurality of available key switch arrangements for the CRT key station.
Abstract: A system for driving a flexible magnetic disk including a direct current stepper motor having a shaft directly connected to the disk drive hub. Motor controller means activate the motor to bring it from rest up to a desired speed, e.g., 360 rpm, and thereafter maintain the speed constant. The motor controller initially provides a detent pulse to move the rotor to a starting position and then provides pulses of decreasing duration and increasing frequency to accelerate the motor to the desired speed.
Abstract: A tape transport system having a capstan servomechanism for velocity control of tape across a read/write head and separate reel servomechanisms for tape supply and take-up control, and also having tape loops in vacuum columns, is provided with tape position feedback to each reel servomechanism to stabilize reel positions in a standby (zero capstan speed) condition from AC tachometers of the induction-generator type normally used during steady state (steady capstan speed) for velocity feedback.
Abstract: Means for making field alignment of transducers with reference tracks prerecorded on a master disc comprising a source of regulated voltage, a separate potentiometer associated with each selected transducer, a separate switch coupling each potentiometer to a summing junction of a positioner servo-control circuit common to all transducers, and means responsive to transducer selecting signals for turning on the coupling switch of the associated potentiometer.
October 24, 1974
Date of Patent:
April 27, 1976
James L. Scieszinski, Ericsen M. Dunstan, Sidney T. Schell
Abstract: A clock pulse generating system is disclosed for recovery of read data from magnetic record media comprised of a phase-locked loop for tracking data pulses. The loop employs simple digital logic gates for phase error detection, third-order filtering for the transient phase and frequency error reduction and a voltage controlled oscillator (VCO) comprised of a capacitor charged by current from a voltage controlled current source, voltage threshold detection means, and means responsive to the threshold detection means to quickly discharge the capacitor. The VCO includes a flip-flop at its output to produce a square-wave feedback signal to the phase detection gates and to a data recovery circuit.
Abstract: In a flexible magnetic disk drive apparatus including a housing having an entrance slot for receiving a disk carrying cartridge, means for engaging said cartridge to either properly position it relative to a disk clamp and drive mechanism or eject it out through said entrance slot. The means is comprised of a fixed positioning surface or flange located adjacent to said entrance slot and a spring mounted ejector member for engaging the leading edge of said cartridge to urge the cartridge trailing edge against said positioning surface.